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This study aims to verify the dose delivery of prostate radiotherapy treatments in an adult pelvic phantom with two metallic hip and femur prosthesis using a four-field box technique. The prostate planned target volume (PTV) tridimensional (3D) dose distribution was evaluated using gel dosimetry, and thermoluminescent dosimeters (TLD) were used for point-dose measurements outside it. Both results were compared to the treatment planning system (TPS) dose calculation without using heterogeneity corrections to evaluate the influence of the metal in the dose distribution. MAGIC-f gel dosimeter (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper with Formaldehyde) associated with magnetic resonance imaging was used. TLD were positioned at several points at the bone metal interface and the sacrum region. The comparison of the gel measured and the TPS calculated dose distributions were done using gamma analysis (3%/3 mm), and a pass rate of 93% was achieved. The TLD dose values at the bone-metal interface showed variations from the planned dose. However, at the sacrum region, where the beams did not intercept the prosthesis, there was a good agreement between TPS planning and TLD measurements. Our results show how the combination of 3D dosimetry and measurements at specific points in the phantom allowed a comprehensive view of the dose distribution and identified that care must also be paid to regions outside the PTV.

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Introducción: la funcionabilidad de los artificios protésicos de miembros inferiores suele expresarse en términos de relacionar sus beneficios operacionales con aquellas necesidades funcionales y de bienestar del amputado. Este bienestar se relaciona fundamentalmente con un mínimo gasto energético del paciente y con la ausencia de enfermedades en las articulaciones residuales y que se inducen por la prótesis durante el régimen de marcha. Objetivo: evaluar la funcionabilidad de prótesis transfemorales utilizadas en Cuba mediante la integración de los resultados del análisis cinemático de la marcha del amputado, combinados con análisis de mecánica de sólidos rígidos aplicando simulaciones numéricas. Métodos: el análisis de la marcha de 8 pacientes con amputaciones unilaterales transfemorales y 5 sujetos normales (control) se realizó mediante técnicas videográficas. Se efectuó la estimación dinámica de las fuerzas que actúan en los segmentos articulares y se determinaron las tensiones y deformaciones que sufren las zonas del muñón y de la articulación del tobillo mediante el método de los elementos finitos. Resultados: cambios significativos en la dinámica de los segmentos articulados del tobillo-rodilla y cadera se reflejan como el resultado de la asimetría de la marcha del miembro protésico y el sano. Tal desequilibrio sugiere ser una de las principales causas de las enfermedades degenerativas de la cadera observadas en este tipo de paciente. Conclusiones: el análisis de la funcionabilidad de los artificios protésicos transfemorales solo es posible mediante la integración de los métodos cinemáticos de caracterización de la marcha, métodos dinámicos que establezcan la posibilidad de replicar la actividad del miembro sano. Mediante este estudio fue posible además el estudio de la resistencia mecánica y se vincularon todos los resultados a la aparición de enfermedades tanto en el miembro intacto como en el residual

Introduction: the functional quality of the prosthetic devices of lower extremities is usually expressed in terms to relate the functional benefits to those functional needs and the wellbeing of the amputee. This wellbeing is related mainly to a minimal energetic output of patient and to the lack of diseases of residual joints induced by the prosthesis during the gait. Objective: to assess the functional qualities of trans-femoral prostheses used in Cuba by the integration of results of kinematics analysis of the gait of amputee, combined with mechanics analysis of rigid solids applying numerical simulations. Methods: the gait's analysis of 8 patients with trans-femoral unilateral amputations and 5 normal subjects (controls) was made by videographic techniques. The dynamics estimation of strengths acting on the articular segments was carried out and determination of strain and deformations suffering the stump zones and of the ankle joint by finite elements method. Results: the significant changes in the dynamics of ankle-knee-hip articulation segments are present as the result of gait asymmetry of the prosthetic limb and the healthy one. This imbalance may be one of the leading causes of degenerative diseases of hip observed in this type of patient. Conclusions: the analysis of functional qualities of trans-femoral prosthetic devices only is possible by means of the integration of cinematic methods of gait characterization, dynamic methods establishing the possibility to replicate to the activity of healthy limb. Using this study also it was possible the mechanical resistance study linking all results to the appearance of diseases of intact limb as well as the residual one

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O objetivo deste estudo foi determinar a viabilidade de produção de uma prótese femoral de titânio garantindo a qualidade da matéria prima e as características das superfícies. Um protótipo foi criado pelo Método de Elementos Finitos em AutoCad® 2000. A simulação dos esforços demonstrou uma tensão de von Mises 8,1 vezes menor que a tensão crítica para escoamento do material. Na determinação dos constituintes metálicos, obteve-se: Fe  =   0,06%, Al  = 6,20%, V  = 3,57%, O  = 0,115%, N  = 0,003%, H  = 0,010%, e ausência de metais pesados. As propriedades elasto-plásticas da amostra tiveram valor médio de dureza de 4,45 (3,92 a 4,79) GPa e o módulo de elasticidade variou de 112,12 a 140,77  GPa (média  = 134,33). O coeficiente de rugosidade médio (DP) no cone foi de 0,60  (0,03) μm; na região jateada de 12,2 (0,8) μm e na ponta de 0,41 (0,01) μm. Nos ensaios de fadiga e de corrosão não foram observadas alterações. A análisegranulométrica do pó do material depositado demonstrou predominância de partículas médias (75  μm a 180  μm; 84%). A espessura da camada do material depositado apresentou valor médio de 52,7  μm (0 a 318  μm), porosidade média de 16% (variandode 3% a 41%), poros de diâmetro médio de 88,5  μm e profundidade média de 28,2  μm. A tensão (força por unidade de área) de adesão da camada porosa depositada revelou valoresde 15 a 17  MPa. Em conclusão, os resultados dos testes e ensaios técnicos estão dentro das normas internacionalmente recomendadas e padronizadas para implantes metálicos em titânio estando essa prótese de acordo com os padrões internacionaisde qualidade e segurança.

The objective of this work was to study the feasibility of manufacturing a cementless femoral prosthesis in Brazil, in compliance with internationalstandards of quality assurance. A virtual prototype by the Finite Elements Model in AutoCad® 2000 was assessed and demonstrated a von Mises tension 8.1 below the deformation point. In determining the metallic components, the percentages were Fe  = 0.06%, Al  = 6.20%, V  = 3.57%, O  = 0.115%, N  = 0.003%, H  = 0.010% without any contamination due to heavy metals. The elasto-plastic properties showed an average value of hardness of 4.45 (3.92 to 4.79) GPa and elasticity module varied from 112.12 to 140.77  GPa (mean  = 134.33). The average coefficient of roughness (SD) in the cone was 0.60 (0.03) μm, 12.2 (0.8) μm in the plasma spray coating region, and 0.41 (0.01) μm in the tip. In the assays for fatigue and corrosion no changes were observed. The grain size analysis of the deposited material dust demonstrated predominantly (84%) medium size particles (75  μm to 180  μm). The thickness of the deposited material layer presented average value of 52.7  μm (0 to 318  μm), average porosity of 16% (varying from 3% to 41%) and pores of average diameterof 88.5  μm and average depth of 28.2  μm. The force of adhesion of the deposited porous layer showed values between 15  and  17  MPa. Results were in accordance with the norms and tests internationally recommended and standardized for metallic implants in titanium alloy and  the femoral prosthesis manufactured with national technology was in accordance with international standards of design, quality and safeness.

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